Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
l=[[1]*(w+2)]+[[1]+[1 if i=="#" else 0 for i in input()]+[1] for i in range(h)]+[[1]*(w+2)]
c=[[0]*(w+2) for i in range(h+2)]
q=[(1,1)]
e=[(0,1),(0,-1),(1,0),(-1,0)]
kyori=1
while len(q)>0 and c[h][w]==0:
    tl=q
    q=[]
    for x,y in tl:
        for X,Y in e:
            if(l[y+Y][x+X]==0 and c[y+Y][x+X]==0):
                q.append((x+X,y+Y))
                c[y+Y][x+X]=1
    kyori+=1
if  c[h][w]==0:
    print(-1)
else:
    print(sum([i.count(0) for i in l])-kyori)